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Old 01 April 2012, 18:00   #1
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Less information on Garmin charts?

Hello

I'm a tad disappointed in the quality of the UK mapping that comes supplied with my Garmin 451S; this seems to be a data issue rather than the chart plotter per se, as the data issues are there in Homeport too.

So I wondered if I was missing something here, or what others do to get around this.

For example, the attached two chart extracts show the same area on a (scanned in) Admiralty paper chart and the Garmin G2 vector chart (as viewed in Homeport).

To me, I can just see so much more information at a glance (in the same physical map/screen area) on the Admiralty chart than the Garmin one.

The biggest issue for me (from what I've noted so far) is that the Admiralty chart differentiates between the rocky and sandy areas (in green) on the edge of Newark Bay, whereas the corresponding green area on the Garmin chart does not so differentiate (even if fully zoomed in).

Also when you look at the island of Copinsay, I just find the Admiralty chart gives you all you need to know at a glance, whereas the Garmin chart only shows the jetty when you are fully zoomed in. It also doesn't show the very obvious track up to the lighthouse.

So my questions are:
1 - is this just an inherent limitation of these Garmin maps?
2 - are the G2 vision charts any better (in terms of charted data and/or the air photos0?
2 - is there a way to show the beach/sand areas in the "green" zones, or the jetty, without having to zoom in so much?
3 - can the Admiralty charts be imported to use as an overlay in Homeport or the chart plotter?

Of course it's great having all the tidal info etc embedded in the Garmin maps, but for me the first priority is the chart data.

Many thanks for your help

Best wishes

Steve
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Old 01 April 2012, 18:12   #2
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i thought the G2 charts were being phased out only the vision versions would be available now? sure someone will put me right
the G2 vision chart is good, i think the biggest benefit of the plotter is being able to use it at speed in an open rib when a paper chart would be next to useless. but for route planning etc, paper wins every time, and they feel better too
i believe you can get updates of garmin website now, just plug your card in and get your plastic out, maybe the update would solve your problem?
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Old 01 April 2012, 18:38   #3
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Hello Chris - thanks for that.

To help clarify, the extract is from the preloaded G2 UK and Ireland maps. My understanding is that the G2 Vision charts are the same, but what you get extra is aerial photography, fisheye view and the ability to do auto route planning.

But, like you, I hope someone with more experience can help.

Best wishes and thanks again

Steve
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Old 01 April 2012, 19:25   #4
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I've always found the Garmin digitised charts to show less info than a paper chart, with the exception of Lowrance which impressed me on a small early plotter of theirs. Re your Garmin, have you got the detail option set to max? You can control how much it shows at different zoom levels on all the plotters I've used and Homeport.
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Old 01 April 2012, 20:46   #5
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I've used Garmin charts for 11 years in all forms and always found them to be excellent, check you plotter settings, you will never want the same detail as a paper chart unless you had a 50" screen.
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Old 01 April 2012, 22:16   #6
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Did you not ask this question and be told Navionics were much better than garmin about a month ago?
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Old 03 April 2012, 11:16   #7
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Hello All

Many thanks for this.

Yes - the view detail is set to maximum, so it just seems that the way the Garmin chart has been digitised (or the data source) has not differentiated between rock and sand in the intertidal zone.

I understand the issue about screen size, but when looking at an individual bay, screen size is not a limitation on this sort of detail.

I was wondering if people had been able to import a georeferenced raster scan of the Admiralty charts (ie bought or scanned in and used as a separate layer) when such detail was missing? Can be done on PC systems, but curious to see if this has been achieved on a dedicated chart plotter.

Hi Bruce - yes it is true in that some people said Navionics, whereas other sources and private messages also felt Garmin was better. Plus the issue was made on hardware considerations too.

The difficulty is that until you see the charts side by side it's difficult to make a fully informed decision.
Curious to know if the Navionics charts do show the difference between sand and rock, as I've not seen that clarified anywhere?

Equally, there's lots that's good about the Garmin; I just find it surprising to omit showing the difference between rock and sand in the intertidal zone... But then for many users who don't do beach landings and only go to harbours/marinas, it won't be an issue.

But it is helpful information for the more adventurous of us, like Ribbers and Kayakers etc. Of course, the chart is only one bit of information you'd want, especially given how sand shifts around up here, but a good starting point all the same. A set of laminated hard copy chart extracts will be going with me anyway :o)

Best wishes and thanks again - and hopefully this thread helps any other users for whom this rock/sand would be an issue.

Steve
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Old 03 April 2012, 15:56   #8
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PS - just in case it helps to illustrate the point, this is a picture of Newark Bay taken today on the dog walk, illustrating the change from rocky shore to large beach, areas which the Garmin maps show as being all the same.

I may well take this up with Garmin, as it could potentially be an issue that only affects certain areas.

Cheers

Steve

Also shows our local slip in the foreground...
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Old 03 April 2012, 18:41   #9
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IMHO if you want to plan a voyage use a current paper and/or raster charts. Don't forget to check the Notices to Mariners (or whatever those updates are called in the UK). While underway to confirm your route and know where you are, that's when the GPS chartplotter is used.

The Navionics gold does not distinguish rock from sand either. Some of the modern cutting edge formats (platinum with embedded photos etc) may incorporate that information. I still wouldn't trust when rock changes to sand or vice versa to route planning, that's potentially way too dynamic anyway.
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Old 06 April 2012, 23:47   #10
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I still wouldn't trust when rock changes to sand or vice versa to route planning, that's potentially way too dynamic anyway.
Sand or rock, I find it best to avoid anything solid in route planning
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Old 07 April 2012, 03:47   #11
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So back in the day we used to do a lot of GIS work, and although Raster Maps were great, they took up LOADS of room compared to the vector equivelant.

I'd also go with both, do your planning on the charts and then wack it into the GPS / Homeport. I'm sure as time goes on the vector maps will get there (and there nearly there now). But theres nowt like pouring over a chart!
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Old 07 April 2012, 11:13   #12
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. But theres nowt like pouring over a chart!
Aye, don't you just hate it when that happens
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Old 14 April 2012, 16:35   #13
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Hello All

Thanks for all this.

Good to know this isn't just an issue with Garmin maps for a start, as otherwise I'm very pleased with the unit.

Secondly, good to know I'm not overlooking something here about the missing data.

While of course one should not just rely on one data source (and I love paper charts anyway), and features like the sand/rock areas can change, I still find it disappointing that this data is not digitised and thus not available on the maps supplied.

Clearly the Admiralty see it as valuable to plot these data on their charts, and if - say - in an emergency etc, I feel it would be helpful to have these data on the Garmin G2 charts to tell you, eg, at the time of survey this bit of coast was sandy and this bit was rocky. By them merging those two areas when digitising the charts, it denies the helm the opportunity to make such judgements.

I hope this thread helps others though, as this is one of the things that you don't find out until you actually buy. Certainly I feel users can be forgiven for expecting the sand/rock data to be shown, especially when the maps are promoted as:

"Features include shading between depth contours, spot soundings, navaids, port plans, wrecks, obstructions, intertidal zones, fishing charts, restricted areas and more... these charts also remove navigation information from the map to reduce clutter and give clearer definition to the sea floor, ideal for fishing." and more at Garmin | United Kingdom | Maps - BlueChart

Hopefully it also helps those people who may not appreciate how data quality or usefulness can be compromised in the vector maps, depending on the application. Certainly there's a very similar analogy with the Ordnance Survey Explorer maps and the corresponding digitised data. Horses for courses :o)

Off now to produce my own waterproof chartlets as backup anyway, thanks to the really helpful folk at: Free charts and pilotage

Once again, many thanks to you all for your input on this

Best wishes

Steve
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Old 15 May 2012, 04:10   #14
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Just a quick note on the charts and Digital charts from a commercial, large vessel navigator.

The advent of ECDIS (Electronic chart display and information systems) has required the Admiralty, (plus many othe National hydrographic offices) to be working flat out over the last 15 to 20 years to digitise all the information on all of the charts they publish worldwide.

Raster charts are NOT reccomended for navigation when scaling up as they are basically digitally scanned copies of the paper charts, and significant scaling errors may be encountered when zooming in to show details.

Vector charts on the other hand have to have each individual piece of data assigned a Lat/Long, so that when sclaing in the position/relationship to other information does not change, and the information stored can be interrogated.

Obviously if you see the amount of data points on each chart, and then see the work that goes into digitising this, multiply that by the admiralty worlwide folio of more than 3,000 charts, this becomes a massive undertaking.

Commercial ships are required to start carrying ECDIS from this year, and we must use IMO compliant vector charts, which must be oproduced by a national hydrogaphic office, or get the information from one, and make the charts to a recognised IMO standard. I would suggest that the Garmin charts are not IMO compliant, which is why they are cheaper than the Admiralty charts.

Currently we pay over 30 pounds for each admiralty chart, and a full folio of charts is an extremely expensive set of charts, equally as is the full vector folio worldwide, and these still do not have the same level as detail as the paper chart, simply because the commercial side of shipping does not need that level of detail.

I still am old school, and love the paper charts, even though the writing is on the wall for them, but as far as I am concerned paper charts do not stop working when the sattelites fall out of the sky! all electronic ones can and are affected by interference/jamming and are subject to the whims of a country who owns the system who can turn off the civilian side of the signals!

I still believe google earth, and sattelite pictures are fantastic for determining coast, and close inshore topography, as long as the area is covered that is!

Rant over!
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Old 15 May 2012, 08:12   #15
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Charts are always going to have more detail it seems. Best use chart for planning purposes and then electronic chart plotter for ease of use. As my Garmin unit is now too old to be able to have newer maps put on I have recently done some research looking at newer types of elctronic charts and got some feedback from various sources, it looks to me like the Navionics charts are the way to go som im getting a RayMarine e7 with the gold chart package.
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Old 15 May 2012, 08:41   #16
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Navionics

I have just got the Navionics Gold UKI&Holland for my Lowrance HDS-5. The 'free' updates of NM's etc for a year is really good - but you will miss Mapsource for viewing, planning and waypoint management on your PC with Garmin.
The Navionics free version is very poor (IMHO)
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Old 01 August 2012, 13:44   #17
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Hello All

Many thanks for this.

While I agree about the enlarging of raster maps, what I like about viewing raster maps (I use them in other non-marine applications for work) is that you know the accuracy and limitations of the data, and it's very apparent when you zoom in too much.

What concerns me is that we seem not to know the digitising accuracy of the vector maps derived from paper/raster maps.

I've seen many cases where people believe the in the infinite accuracy of vector maps (as the screen lines don't get thicker when you zoom in) when it truth they are no better, and may well be worse, than the raster maps.

I'm sure as the commercial, full price digitised charts are produced, the accuracy will be there, but I've so far not been able to get any data on the accuracy of the Garmin maps.

And of course, we have to press the button to agree to "not for navigation" each time we power up (at least on my Garmin chartplotter), so that's there get out I guess. But Garmin must know the reality of how people use their chartplotter and data.

But personally, I'd like a choice of charts with known accuracy, and maybe a choice to pay more for those with a more transparent provenance / greater accuracy.

Thanks for the contributions and good to have the debate, as I'm sure some people do not realise the potential errors that digitising can in theory introduce at the budget end of the market.

Best wishes for now

Steve
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Old 01 August 2012, 17:51   #18
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Unless the digital chart producers go and re-chart all the seas then we will never have totally accurate detail on our charts. Most of the data comes from soundings and charting taken in the 1800's round our way with one or two areas slightly more up to date having been done in the 1960's! Not only that, but some charts have been scanned slightly out of sync. This is something I identified on an early Garmin chart of Alderney. They acknowledged and agreed there was an error when I told them and I think it has now been rectified.
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Old 01 August 2012, 19:18   #19
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Hello Erin

Thanks for this - I quite agree re coverage... Indeed up here we still have areas that have never been surveyed and so are basically blank on the Admiralty paper charts (apart from the word "unsurveyed) or as they put it on the Garmin chart "inadequately surveyed area". Indeed, there's the pretty accurate saying that any map or chart is out of date as soon as it's printed.

The issue of concern to me though was that of the accuracy of digitisation. Or in other terms:

1 Any chart or map is an interpretation of the real word based on certain rules on what to show and how.

2 For the paper charts were are used to (and love) those rules are pretty well known and documented

3 When people then (eg like Garmin and everyone else) produce digitalised maps from the latter data, they too are further interpreting the existing map/chart according to their chosen rules of interpretation and accuracy.

4 The drawback I've found with the Garmin charts is that one does not know the limitations imposed in the interpretation, until you start to compare with the paper charts... Eg Garmin have chosen to not differentiate between rocky and sandy areas, and where there's lots of rocks/obstructions in a small area (as shown in detail on Admiralty charts), Garmin just put a general notation over the whole area as "Danger area".

5 So basically Garmin (and all the other firms I'm sure) are adding an additional degree of interpretation of the "real world" and potential for additional inaccuracies creeping in. When letting digitising contracts, such details are specified so you know what you are getting, whereas as a consumer of Garmin charts, I've not been able to find out what spec they work to... But if anyone knows, that would be helpful.

Hopefully that explains the issue a little better....? (though it is a bit of a techie issue :o) ) Basically about data interpreation than coverage

Best wishes

Steve
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Old 01 August 2012, 20:05   #20
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I'm not sure who currently digitises Garmin charts, but it was I believe Transas whom I were told are Russian based. I agree with what you say about interpretation, although I would clarify that to some extent and say that it is as much to do with their choice of symbols and abbreviations as it is their interpretation and generalsiation. As you say, they group or cluster rocks and features and just give a generic hatching or splodge of colour rather than keep the detail that a paper chart would show. I als find that some of the symbols are not very clear or are too general and I quite often find the text is the wrong scale or badly positioned. It even moves around as you zoom in which makes identifying certain features or places rather tricky.
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